1. Field of the Invention
The present invention relates to a brake device provided to an air motor of a pneumatic rotational tool.
2. Description of the Related Art
A pneumatic rotational tool, e.g., a grinder or a driller, is used for grinding and drilling various types of materials. In a pneumatic rotational tool of this type, two ends of a rotary shaft of a lightweight motor, e.g., an air turbine driven by compressed air are rotatably supported by bearings, and supply and the prevention of the supply of the compressed air to and from the turbine, respectively, are accomplished by an appropriate valve means.
According to the lightweight air motor of this type, the motor is not stopped immediately after supply of air is stopped by the valve means, unlike in a vane-type air motor, but continues to rotate for a long period of time because of the inertia of a rotating member depending on the types and characteristics of the rotational tool.
However, if rotation of the pneumatic rotational tool continues for some time even after the valve means is closed, problems arise in terms of safety. In addition, since the following operation or process cannot be smoothly started, the workability is poor.